Crossword clue: a mixture of lime or gypsum with sand and water; hardens into a smooth solid; used to cover walls and ceilings

The most common answer is plaster (7 letters).

1 answer found in Letterora's clue database (Wikidata facts, Open Trivia DB, WordNet and Webster definitions — all licensed sources).

Possible answers

plaster 7 letters wn-def

a mixture of lime or gypsum with sand and water; hardens into a smooth solid; used to cover walls and ceilings